U.S. Pat. No. 6,901,850, which is incorporated by reference, discloses an injection head for an injecting machine intended for injecting brine to meat pieces on a support surface of a meat conveyor. The injection head comprises a main body and a plurality of parallel hollow needles that can be retracted with respect to the main body against elastic means acting on an upper end of each needle opposite the tip thereof. In the injecting machine, the head is actuated by driving means to vertically reciprocate between an upper position, in which the tip of said needles is at a distance from the support surface of the conveyor sufficient for enabling the meat pieces to pass under the injection heads, and a lower position, in which said lower needle portions of the needles are stuck into the meat pieces located under the injection heads. Brine supplying means are provided for supplying brine to an inlet opening of each needle when the injection heads are in said lower position.
It is also known to provide an injecting machine with two or more injection heads of the type described above installed at the same level over the support surface of the conveyor for consecutively injecting brine to meat pieces on the support surface of the conveyor in order to increase the amount of total brine injected into each meat piece. However, due to the fact that the volume of a meat piece increases significantly when brine is injected therein, in some instances a particular meat piece previously injected by the first injection head in relation to a conveyor forward direction cannot pass under the second injection head due to the volume increase undergone with the first brine injection. To solve this, the injection heads would need to have an enlarged stroke length between their upper and lower positions with increased manufacturing costs.